1. Field of the Invention
The present invention relates generally to a liquid crystal display(LCD) module, and more particularly, to an LCD module in which a lamp cover and a rear reflector plate have improved structure and coupling arrangement, thereby preventing “wrinkling appearance” caused at a rear reflector plate and “light leakage” caused between a lamp cover and a rear reflector panel.
2. Description of the Related Art
LCDs are commonly used as an information display device. From among LCD components, a backlight unit plays a significant role since its structure affects on the size and light efficiency of LCD, and further on the overall mechanical and optical characteristic of LCD.
Backlighting structure for an LCD display is disclosed in detail in U.S. Pat. No. 5,567,042 “Reflector for flat panel display backlight unit”, U.S. Pat. No. 5,592,193 “Backlighting arrangement for LCD display panel”, U.S. Pat. No. 5,608,553 “Back light for liquid crystal display”, and U.S. Pat. No. 5,640,483 “Backlighting system utilizing total internal reflection”.
In such a conventional backlighting structure, a series of sheets are interposed between a front surface of a light guide plate and a liquid crystal display panel, and a rear reflector plate is interposed between a rear surface of the light guide plate and a mold frame. In this case, the stacked sheets contribute to improvements in viewing angle and luminance of light emitted from the front surface of the light guide plate, while the rear reflector plate serves to direct the light leaked through the rear surface of the light guide plate toward the front surface of the light guide plate.
A lamp to be used as a light source is disposed in a portion of the light guide plate, being covered by a lamp cover.
Here, the lamp cover is bent into a square C shape, for instance, and fitted to a side portion of the light guide plate in such a manner that an end of the lamp cover directed toward the light exit area is elongated significantly toward a light entrance area of the light guide plate. Then, upper and lower plates of the lamp cover directed toward the light exit area are overlapped to the upper and lower surfaces of the light guide plate directed toward the light entrance area of the light guide plate.
In this case, if the lamp cover having an end thereof directed toward the light exit area and which is elongated, is fitted to a side portion of the light guide plate, the lower plate of the lamp cover directed toward the light exit area strongly presses the rear reflector plate, since the rear reflector plate is arranged at the rear surface of the light guide plate. Such a structural characteristic of the backlight unit affects adversely to an overall display quality of the device.
For example, if the lower plate of the lamp cover directed toward the light exit area presses too strongly the rear reflector plate, a deformation may be caused onto the rear reflector plate due to a pressing force transmitted from the lamp cover, thus resulting in a so-called “wrinkling appearance”.
For another example, if the lower plate of the lamp cover directed toward the light exit area presses with a lower intensity the rear reflector plate, a gap is produced between the rear reflector plate and the lamp cover, resulting in a “light leakage” where a light emitted from the lamp is leaked at the lower plate of the lamp cover directed toward the light exit area.
In a conventional manufacturing procedure, a gap of the lamp cover is controlled during an assembly work for a backlight unit, to thereby control the degree of pressing exerted onto the rear reflector plate by the lamp cover, so that in-advance prevention against the above-mentioned wrinkling appearance and light leakage can be obtained.
However, the wrinkling appearance and the light leakage have a close relation with each other. That is, if the degree of pressing exerted onto the rear reflector plate by the lamp cover is raised in order to prevent a light leakage, a wrinkling appearance may be caused at the rear reflector plate by the increased pressure applied thereto. On the contrary, if the degree of pressing exerted onto the rear reflector plate by the lamp cover is lowered so as to prevent a wrinkling appearance, a light leakage may be caused by the reduced pressure applied to the rear reflector plate. In summary, conventional approaches have failed in obtaining a simultaneous prevention against wrinkling appearance and light leakage.